Turbo Conversion Gone Bad - MAC 11C Troubleshooting

[scott thomas]

I've been there several times. The car will run until a certain
point. Poorly, at that. After the threshold, the engine will not
start, but once running, it will stay running if the timing goes way
off.

The most recent time was with my broken timing pin. Before it broke,
it was bent. Black smoke, popping, no power, tons of boost. The ecu
doesn't check for cam timing. It only infers from the distributor
angle, too.

I can remember what the alignment threshold is, but it's a
measurable amount.


---- Begin Original Message ----

From: "Nate Stuart" <newt at newtsplace.com>
Sent: Wed, 27 Aug 2003 16:30:35 -0400 (EDT)
To: "scott thomas" <scott at dreamtheater.zzn.com>
CC: blarson at zeiss.com, quattro at audifans.com
Subject: Re: Turbo Conversion Gone Bad - MAC 11C Troubleshooting


scott thomas said:
> I thought the MFTS has to be connected.

Nope.

> Next, I'd verify the engine timing. Use the flywheel mark
> and not the crank pulley. Make sure it lines up with the cam, then
> line it up with the distributor. Sounds like something that
happened
> to me. The timing was of, but the engine still ran, so it was the
> last thing I checked.

The MAC11 won't fire the coil if the timing is 'off' it's a go no-go
sitation for the computer. The ignition pulse is all computer
controlled,
you cannot adjust the timing from the distributor, it has to be done
within the ECU. The distributor only points to the plug lead to send
the
spark too, and has a hall sendor to tell the ECU when the engine is
near
TDC compression stroke for Cyl 1. Once the ECU sees this it figures
out
the timing from the flywheel sensors. If the dizzy is to far off the
ECU
will never see the flywheel pin inside the time that the TDC window
is in
front of the hall sendor in the distributor, and you will never get
spark.


---- End Original Message ----




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